L. Greiner 1SLAC Test Beam 03/17/2011
STARSTAR
LBNLLeo Greiner, Eric Anderssen, Howard Matis,
Thorsten Stezelberger, Joe Silber, Xiangming Sun, Michal Szelezniak, Chinh Vu,
Howard Wieman
UTAJo Schambach
IPHC StrasburgMarc Winter CMOS group
STAR Pixel Detector
A MAPS based vertex detector for STAR
Short description of the detector and why we need test beam
L. Greiner 2SLAC Test Beam 03/17/2011
STARSTARVertex Detector Motivation
Direct Topological reconstruction of Charm
Detect charm decays with small c, including D0 K
Method: Resolve displaced vertices (100-150 microns)
L. Greiner 3SLAC Test Beam 03/17/2011
STARSTARInner Detector Upgrades
TPC – Time Projection Chamber(main tracking detector in STAR)
HFT – Heavy Flavor Tracker SSD – Silicon Strip Detector
r = 22 cm IST – Inner Silicon Tracker
r = 14 cm PXL – Pixel Detector
r = 2.5, 8 cm
We track inward from the TPC with graded resolution:
TPC SSD IST PXL~1mm ~300µm ~250µm vertex<30µm
L. Greiner 4SLAC Test Beam 03/17/2011
STARSTARPXL Detector Mechanical Design
Mechanical support with kinematic mounts (insertion side)
Cabling and cooling infrastructure
Insertion from one side2 layers5 sectors / half (10 sectors total)4 ladders/sector
MAPSRDObuffers/drivers
4-layer kapton cable with aluminium tracesAluminum conductor Ladder Flex Cable
Ladder with 10 MAPS sensors (~ 2×2 cm each)
carbon fiber sector tubes (~ 200um thick)
20 cm
L. Greiner 5SLAC Test Beam 03/17/2011
STARSTARDetector Characteristics
Pointing resolution (12 19GeV/pc) m
Layers Layer 1 at 2.5 cm radiusLayer 2 at 8 cm radius
Pixel size 20.7 m X 20.7 m
Hit resolution 6 m
Position stability 6 m rms (20 m envelope)
Radiation length per layer
X/X0 = 0.37%
Number of pixels 356 M
Integration time (affects pileup) 185.6 s
Radiation requirement 20 to 90 kRad 2*1011 to 1012 1MeV n eq/cm2
Rapid detector replacement
< 8 Hours
356 M pixels on ~0.16 m2 of Silicon
L. Greiner 6SLAC Test Beam 03/17/2011
STARSTARTest Beam use
2011• Characterize pre-production prototype sensors in a
beam telescope configuration to check efficiency and resolution as a function of bias and discriminator settings for MIPS.
2012 • Prototype sector and detector tests. Test tracking with
MIPs through 4 layers of detector. Track stability with cooling air flowing.
2013• Production sector and detector tests. As above.
MAPS sensor characteristics:Column parallel RDO with in-chip CDS, discriminators and zero-
suppression.
L. Greiner 7SLAC Test Beam 03/17/2011
STARSTARParameters required for Beam Tests
Beam parameters Value Comments
Particle Type MIP
Energy MIP
Rep Rate NA
Charge per pulse Low / diffuse 1k / spill
Energy Spread NA MIPs
Bunch length rms NA
Beam spot size, x-y Minimum 3cm x 3cm
Others (emittance, …)
Logistics Requirements
Space requirements (H x W x L) 2011 – 3’ x 3’ x 1’ for telescope2012/2013 – 2’ x 6’ x 2’ + blower
Duration of Test and Shift Utilization
1 shift – setup3 shifts data taking
Desired Calendar Dates Spring/summer 2011, 2012, 2013
L. Greiner 8SLAC Test Beam 03/17/2011
STARSTARBeam Test Packages
Beam Telescope
Sector and detector apparatus with air cooling housing and blower
L. Greiner 9SLAC Test Beam 03/17/2011
STARSTAR
backup
L. Greiner 10SLAC Test Beam 03/17/2011
STARSTAR
2 m (42 AWG TP)6 m (24 AWG TP)
100 m (fiber optic)
Highly parallel system
4 ladders per sector 1 Mass Termination Board (MTB) per sector 1 sector per RDO board 10 RDO boards in the PXL system
RDO motherboard w/ Xilinx Virtex-5 FPGA
RDO PC with DDL link to RDO board
Mass Termination Board + latch-up protected power daughter-card
PXL Detector Basic Unit (RDO)
Clk, config, data, powerClk, config, data
PXL built events
L. Greiner 11SLAC Test Beam 03/17/2011
STARSTARMonolithic Active Pixel Sensors
• Standard commercial CMOS technology • Room temperature operation• Sensor and signal processing are integrated in the same silicon wafer• Signal is created in the low-doped epitaxial layer (typically ~10-15 μm) → MIP
signal is limited to <1000 electrons• Charge collection is mainly through thermal diffusion (~100 ns), reflective
boundaries at p-well and substrate → cluster size is about ~10 pixels (20-30 μm pitch)
• 100% fill-factor • Fast readout• Proven thinning to 50 micron
MAPS pixel cross-section (not to scale)
L. Greiner 12SLAC Test Beam 03/17/2011
STARSTARMimosa-26 Efficiency vs. threshold
L. Greiner 13SLAC Test Beam 03/17/2011
STARSTARMimosa-26HR eff vs. fake hit rate
L. Greiner 14SLAC Test Beam 03/17/2011
STARSTARRDO System Design – Physical Layout
1-2 mLow mass twisted pair
6 m - twisted pair
Sensors / Ladders / Sectors(interaction point)
LU Protected Regulators,Mass cable termination
RDO Boards
DAQ PCs(Low Rad Area)
DAQ Room
PowerSupplies
Platform 30 m
100 m - Fiber optic30 mControl
PCs
30 m
L. Greiner 15SLAC Test Beam 03/17/2011
STARSTARPXL RDO Architecture (1 sector)
Ladder x 4
FPGA
LU p
rot.
pow
er
MTB x 1 PowerSupplies
ControlPCs
Trigger
DAQRDO PCsSIU
ADC
USB
i/o
RDO board x 1
Sensor testingProbe testingSRAM
Black – cfg, ctl, clk. pathBlue – data pathRed – power / gnd pathGreen – testing path
fiber
Unified Development Platform